Alignment independent and self-aligning inductive power transfer system using mobile, flexible inductors

ABSTRACT

An inductive power transfer device is provided for recharging cordless appliances. The device includes a plurality of inductors arranged in an array and connected with a power supply via switches which are selectively operable to activate the respective inductors. The inductors serve as the primary coil of a transformer. The secondary coil of the transformer is arranged in the appliance. When the appliance is arranged proximate to the power transfer device with the respective coils in alignment, power is inductively transferred from the device to the appliance via the transformer.

REFERENCE TO PRIORITY DOCUMENTS

This application claims priority to under 35 USC §120 and is acontinuation of U.S. patent application Ser. No. 10/960,102, filed Oct.8, 2004, said application Ser. No. 10/960,102 claims priority under 35USC §120, is a continuation-in-part, claiming priority under 35 USC §120to U.S. application Ser. No. 09/702,234, filed in the USPTO on Oct. 31,2001, and issued as U.S. Pat. No. 6,803,744, issued Oct. 12, 2004, whichis incorporated by reference for all purposes. U.S. patent applicationSer. No. 09/702,234 claims priority under 35 USC §119(e) to U.S.Provisional Application Ser. No. 60/162,295 filed Nov. 1, 1999, which isincorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention generally relates to inductive power transferdevices for charging or powering cordless appliances.

Currently, cordless electrically operated devices are charged by asource of electrical energy only when the device and source areconnected to one another. Normally, the source includes some sort ofpedestal to which the device is connected before charging may occur. Thedrawbacks of such an arrangement are self-evident. For example, whenworking with a cordless drill, it is often necessary to mount a batterywhich must be removed from the drill, or the drill itself, on thecharger before the charging process can begin. If the charger is notkept in close proximity, the drill battery must be moved to the charger.The present invention differs significantly from the known prior artwherein the source and devices are specifically matched to only operatewhen the receiver is mounted on the holder for recharging. The presentinvention provides a novel system for automatically charging a devicewhenever it is placed on a rest surface without a direct electricalconnection, regardless of the orientation of the device on the surface.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the invention to provide aninduction power transfer device for an appliance including a housing anda plurality of primary inductors or coils arranged in an array withinthe housing. A circuit connects the inductors with a power supply and aplurality of switches connect each inductor with the circuit. Theswitches are operable to selectively activate respective primaryinductors so that when an appliance having at least one secondaryinductor is placed on the housing, power is transferred to the appliancevia a transformer defined by the primary inductors and the secondaryinductor.

According to a further embodiment of the invention, at least one of theprimary inductors has a longitudinal axis arranged normal to the axes ofthe other primary inductors.

The housing preferably has a flat top wall beneath which the primaryinductors are arranged in a plane parallel to the wall. An applianceplaced on the wall has its secondary inductor inductively coupled withat least one of the primary inductors.

According to a further object of the invention either the inductivetransformer device or the appliance may include an alignment mechanismto assist in aligning their respective inductors to maximize powertransfer.

According to another object of the invention, capacitors are providedfor each primary inductor to balance the inductance thereof.

In accordance with the invention, a user could merely place theappliance such as a cordless power tool, laptop computer, or recordingdevice on a table, shelf or other common storage member and the chargingprocess occurs automatically, regardless of the orientation of thereceiver relative to the charging source. This would result in theappliance being charged whenever it is not in use, rather then merelyresting on a work table between uses as in current practice.

The unique assembly of the present invention assures that the transferof inductive power will occur regardless of the orientation of theappliance relative to the charging source. To achieve this result, thesource may be configured with a number of coils that are arranged inpredetermined positions that optimize the transfer of power to theappliance for certain applications such as a maximum duty cycle, i.e.,power transfer density, or minimum obtrusiveness.

BRIEF DESCRIPTION OF THE FIGURES

Other objects and advantages of the invention will become apparent froma study of the following specification, when viewed in the light of theaccompanying drawing, in which:

FIG. 1 is a front plan view of an induction power transfer device in theform of a table in accordance with the invention;

FIGS. 2-5 are circuit diagrams, respectively, showing various ways inwhich a plurality of inductors is connected in the induction powertransfer device according to the invention;

FIG. 6 is a circuit diagram of the induction power transfer deviceincluding capacitors for inductors;

FIG. 7 is a diagram showing the arrangement of inductors of the powertransfer device and of an appliance to form a transformer;

FIGS. 8 and 9 are front and side views, respectively, of an embodimentof the invention being activated by an appliance;

FIG. 10 is a diagram of a further embodiment of the invention includingannular contacts thereof;

FIGS. 11 and 12 are sectional views showing movable inductors in anappliance for alignment with an inductor of the induction power transferdevice;

FIG. 13 is a diagram showing an alignment mechanism of the invention;and

FIG. 14 is a diagram illustrating a further embodiment of the inventionfor simultaneously charging a plurality of appliances.

FIG. 15 a is a top view of dispersed self-forming flexible inductor(along a z-axis);

FIG. 15 b is self-forming beginning to coalesce;

FIG. 15 c is self-forming inductor fully coalesced.

FIG. 15 d is self-forming (x-y axis) inductor in a relaxed, dispersedcondition;

FIG. 15 e is a self-forming inductor (x-y axis) beginning to coalesce;

FIG. 15 f is self-forming inductor fully coalesced (x-y axis);

FIG. 16 is a cross-section of a self-forming inductor in a top view;

FIG. 17 illustrates a dispersed coils shape memory material is relaxedstate

FIG. 18 illustrates a tightened state of the inductor;

FIG. 19 a illustrates mobile inductor within a housing within anon-aligned load;

FIG. 19 b shows mobile inductor having moved to align with the load;

FIG. 19 c illustrates shows a variant with wheels that can swivel;

FIG. 20 a illustrates shows an additional variant of a mobile inductorfrom a top view;

FIG. 20 b illustrates shows an side view of the additional variantinductor within a housing;

FIG. 21 a illustrates a grid of selectively energize-able circuitelements;

FIG. 21 b illustrates circuit elements selectively energized;

FIG. 22 a shows an array of rotatable conductor elements;

FIG. 22 b shows certain elements rotated as to constitute an inductor.

DETAILED DESCRIPTION

The invention relates to an induction power transfer device which isoperable to charge a cordless battery powered appliance such as a handtool, laptop computer, music player, or the like. In its broadest sense,the invention is a universal inductive interface power connection systemincluding both a powered “source” and a cordless “receiver” which can beused together to transfer power from the source to a variety ofreceivers for charging the same.

The induction power transfer device includes a housing which may takeone of several forms. In FIG. 1, the housing comprises a bench or table2 having a flat upper surface 4. Beneath the surface is a planar arrayof inductors 6 which operate as the primary inductors of one or moretransformers. As will be developed below, each inductor comprises a coilhaving a longitudinal axis. A magnetic core may be provided for eachcoil.

The inductors 6 are connected with an electrical conductor 8 which inturn is connected with a power supply 10. In addition, an electricalswitch 12 is connected between each inductor 6 and the conductor 8 sothat the primary inductors can be selectively activated. For example, inFIG. 1, four inductors 6 are shown, but only the first and fourth havetheir switches closed to supply power thereto for activation.

Resting on the top surface 4 of the table 2 are two appliances, namely,a laptop computer 14 having a secondary inductor 16 and a cordless drill18 having a secondary inductor 20. When the secondary inductors 16, 12are aligned with primary inductors of the power transfer table 2, poweris transferred from the table to the appliances, i.e., the laptopcomputer 14 and the drill 18 via transformers defined by the adjacentprimary and secondary inductors. This power can be transferred to abattery in the appliance to charge the battery in order to power theappliance. Thus, for example, as represented by the block 22 in thedrill 18 of FIG. 1, power from the secondary inductor 20 is supplied toa battery. A switch then activates the motor of the drill for operation.

It will be appreciated by those of ordinary skill in the art that thehousing may take many shapes. For example, it can be formed as anelongated strip or pad on which an appliance may be rested, or a toolbelt against which a power tool can be suspended. With the invention,any time an appliance is not in use, it can be rested or placed on thepower transfer housing and recharged owing to the proximity of theprimary and secondary inductors.

Referring now to FIGS. 2-5, the inductors 6 can be arranged in variouspatterns to insure charging of an appliance regardless of the positionof the appliance on the housing on the power transfer device. In FIG. 2,a plurality of inductors 6 are connected in series with a source 10. InFIG. 3, some inductors 6 a are arranged with their longitudinal axesnormal to the axes of the inductors 6, with all of the inductorsarranged in the same plane. FIGS. 4 and 5 show additional arrays ofinductors in series and square configurations, respectively.

While the drawings illustrate a fixed number of inductors, it will beappreciated that the invention is not so limited and that any number ofinductors may be provided to define an array as large as the housing inwhich it is arranged.

Preferably, the power transfer device inductors are arranged as close aspossible to the inside surface of a protective wall of the housing(FIG. 1) which should be thin enough not to unduly separate the sourceand receiver inductors and thereby diminish the ability to transferpower to the receiver resting on the cover. Advantageously, themultiplicity of source inductors is connected in parallel to pairs ofsupply lines, which pairs of liens extend to the power supply viainterposed coil switches to allow only those coils in proximity to thereceiver to be selectively energized.

In an alternative arrangement shown in FIG. 6, the source coil isenergized through a single supply line provided one coil lead isconnected to the line and the other lead coil is connected to acapacitor 24. To maximize power transfer, sufficient capacitance may beneeded in series with each inductor to keep the current in phase withthe voltage. Accordingly, capacitors are arranged relative to theinterface when the appliance and the source are in mating positions soas to provide capacitive coupling for additional power transfer. Suchtransfer may be weak relative to the inductive transfer generatedbetween the primary coils mounted in the source and the secondary coilsmounted in the appliance.

As stated above, the source inductors may be oriented parallel or normalto the array plane. The inductor coils may include a compressed portionextending substantially parallel to the mating surface (similar to theflat portion of the letter “D” as shown in FIG. 7) to increase magneticpermeation from the source to the appliance. Alternatively, the coilcross-section may be customized to follow the contours of the matingsurface to maximize permeation. The coils may take the form of an aircoil or may have iron and/or other material extending through the coreto improve transmission of the field lines between the source and theappliance.

The core of the inductors may be formed of magnetically permeablefibers, threads or tubes in air or oil or a binding matrix which couldconsist of a viscous fluid or elastomer either of which could bedesigned to soften as the air temperature around the coil rises. Thiswould result in the magnetic core fibers migrating into the mostefficient configuration for transmitting power through the interfacewith the appliance, while avoiding the potential inconvenience of afluid filled array. It will be readily appreciated that, by choosing amatrix configuration which has some compressive strength when not heatedby the presence of an operating interface, the coils within the cord orother array may be protected against crushing when subjected totransverse forces. Alternatively, the core matrix could be fluidized bythe presence of the electrical or magnetic activity at the interfacebetween the source and the appliance, such as by a magnetic core fiberbeing non-aligned with the field lines of the interface, which tends togenerate more heat than an aligned core. The fluid core arrangementallows the cores to configure themselves into the most efficientconfigurations with respect to any established interface configuration,by curving toward the mating surface end of the coils.

The inductors mounted in the appliance should be embedded near thesurface of the device that comes in proximity with the source pad ortable as shown in FIG. 1. For example, the inductor coil(s) may beembedded near the bottom surface of a laptop computer for inductivelycoupling with any source array mounted in a seatback tray on anairplane, train computer table, etc. This would allow the laptop to berecharged while resting or in use. In a similar manner, a power tool mayinclude a coil array positioned adjacent to a surface of the tool thatwould conveniently rest on the source pad, thereby allowing the tool torecharge while laid to rest.

To assure that the appliance will recharge no matter its orientationrelative to the source array, it is preferable that the applianceinclude a set or plurality of inductors, i.e., solenoid coils with somearranged parallel and some arranged normal to the surface of the sourcepad. When the coils are arranged parallel to the surface, they have adispersion of x-y orientations such as a tessellated polygonal or squaregrid, so that at least some of the appliance and source coils are inalignment with each other to allow efficient inductive coupling betweenthe source and the appliance.

In FIG. 7 is shown a further embodiment of an inductive power transferdevice 102 for an appliance 104. The device 102 includes separate coils106, 108, with the coil 106 having a magnetic core 110 contoured to thecore 112 of a secondary coil 114 of the appliance. Each primary coil106, 108 also includes its own power source 116, 118 in lieu of a switchfor activating the coil.

Rectification can be provided to each lead from each coil in the form ofa pair of diodes 120 of opposite polarity on each coil lead with theoutput of each diode feeding the appropriate side of the battery. Inthis embodiment, each increment of power generated in any secondary coilin each inductive cycle caused by the power supply will be captured. Forease of manufacturing, all output leads from the diodes of one polaritycould go “up,” i.e., in the +z direction relative to the x-y plane ofthe array to contact an essentially planar bus such as used in a PCboard comprising the inner side of an appliance array. The otherpolarity diode output leads could go “down,” i.e., -z to a similar buspositioned on the outer side of the receiver cavity.

It is desirable for the source coils to only operate when an applianceis laid to rest on an item containing the source coils. By preventingthe source coils from continuously generating an electromagnetic field,the system would conserve power while eliminating objectionableelectromagnetic fields. This result is achieved by the switches 12(FIGS. 2-5) provided so that each source or primary coil is energizedfrom the power supply only when a secondary coil is within effectiverange and there is sufficient translational and rotational alignmentbetween primary and secondary coils.

Referring to FIG. 7, this arrangement can be achieved by residualpermanent magnetism in the appliance 104 or by a separate magnet 112associated with each secondary coil 114 which operates a magneticswitch, a MOSFET, or similar switch (not shown) to turn the source coilon or off. Alternatively, the coils could be selectively energized by aresonance created between the primary and secondary coils whichresonance amplifies a tiny residual power flow in each source coil. Afurther means for controlling energization may include a piezoelectric,or other oscillator in a tuned circuit pumped by random vibrations whichgenerates feedback amplification when in proximity to a matchedoscillator, thus opening a power transistor and/or OP-AMP between thecoil and supply line once a threshold is reached. The coil switch(including transistor and/or OP-AMP) could also be operated by any kindof tag such as a microchip associated with each receiver coil whichcould generate its own signal (acoustic, radio, etc.) or respond to apolling signal from a matched device associated with each source coil.

In the alternative embodiment of FIGS. 8 and 9, a continuous source coil202 with multiple leads or taps 204, i.e., at regular intervals going tothe supply line, up to the limit of one lead (or tap) per coil going toeach side of the power supply 208 can be provided. A coil switch is onevery lead so that whatever length of source coil is in range of thereceiver coil is activated. A continuous integrated circuit coil switch(“CICCS”) may take the form of a ribbon or strip of a magnetoreactivesemiconductor, possibly organo-polymeric in nature, which goes into itsconductive mode when in the presence of a magnetic field emanating froma secondary coil 210 in close proximity. In one embodiment, a magneticnorth responsive CICCS is deployed to be in continuous contact with onesupply conductor and each coil tap connected to the N-CICCS so thatpower from the supply conductor must traverse the width of the N-CICCSto reach the tap. A south (magnetic) responsive CICCS is similarlydeployed between the coil taps and the other source conductor. When asecondary coil with a permanent magnet 212 as its core is positioned ata position wherein the magnetic fields interact, the N end of the coremagnet opens the N-CICCS and the S end of the core magnet opens theS-CICCS, wherein the points of opening of the N-CICCS and the S-CICCSare separated by exactly the length of the receiver inductor whose coremagnet opened the two CICCs, forming a circuit from one supply line tothe other supply line that extends through the corresponding segment ofthe source inductor coil or a single CICCS could be used in the singlelead with a capacitor scheme. Alternatively, the CICCS could be openedby other conventional devices.

The power supply 208 for generating the electromagnetic field in thesource inductor coils may be either AC or intermittent DC, such ashalf-wave rectified. The power supply may vary at line frequency (60 or50 Hz.) or a power supply with a higher frequency oscillator may beemployed. The inductive power transfer is proportional to dv/dt, minuslosses to self inductance, which increase with increase in frequency.

In another preferred embodiment of the present invention shown in FIG.10, maximum transfer of power is achieved by allowing the coils formingeither the primary 302 or the secondary 304 to move relative to theother set of coils. If one set of coils is allowed to move, i.e., totranslate as much as one-half or more of the intercoil spacing in eitherthe x or y direction or both and to rotate as much as one-half of theintercoil angle or more in either direction about the z axis so that viaan engagement alignment device such as a core magnet the coils or arrayscan achieve maximum alignment when forming a coupled transformer. Toachieve this result, the movable coils or arrays may be set in anon-conductive container or lozenge 306 preferably having an annularconfiguration with connections provided either by flexible wires, or bybrushes and concentric commutators on the lozenge body designed toexclusively contact the appropriate brush. Alternatively, the upper andlower surface of each inductive coil/array-lozenge may functionallyserve as the output brushes for the secondary inductor coils or arrays,which brushes transmit any power generated to the upper and lowerinternal surfaces of the cavity in which the inductor coil/arraylozenges are free to move transitionally and rotationally. Thesesurfaces 308 serve as sliding contacts or commutators, collecting powerfrom the secondary coils and sending it to the device's battery, switchand end user circuitry.

The secondary and/or source coils could also take the shape of flexiblecoils which are free to bend and migrate within a cavity formed ineither the source or appliance device. Alternatively, the flexible coilmay be free from the constraint of any cavity, so as to best align withits mating coil. Motion of the coils (within or without their cavities)is facilitated by a vibrator which is briefly energized when acoil-switch is opened, with the vibrations making it easier for thecoils to migrate into alignment with each other and/or by an activeseeker mechanism (FIGS. 11 and 12) attached to the coil. The vibratorcould be periodically energized. It and the seeker are also usable withany other form of the inductor coils.

The seeker mechanism 402 is attached to any movable source or applianceinductor which mechanism is designed to bring the primary and secondarycoils into ideal alignment for inductive coupling. In FIGS. 12 and 13,the appliance 404 has the movable coil 406. This may be achieved bymeans of a piezoelectric or piezomagnetic leg 408 extending from eachside of the movable inductor 406 to contact the inner side of the matingsurface which is designed to flex (under influence of the electric ormagnetic flux at the interface) in a direction which will move theinductor into alignment with the primary coil 410 as shown in FIG. 12.The legs may be made of materials of opposite polarity in the dorsal andventral region to cause lateral motion. Furthermore, end portions of thelegs may need to have a biased grip to engage the mating surface.Alternatively, the lower leg portions may have a coefficient of frictionwhich varies with the variations in electric or magnetic fields. As aresult, the lower portions of the legs grip the mating surface morestrongly during that phase of the motion which would bring the coil intoalignment. This may apply to a mobile discrete inductor or a flexibleinductor which could be arrayed in their space in an “s” curve to allowmotion of the central portion or other arrangement.

An advantageous form of inductive interface system shown in FIG. 13includes bumps or waffles formed in the exterior surface of the sourcepad 502, which bumps correspond to locations of a source coil or array.The bumps or waffles would mate with indentations in the cover of theappliance coil or array 504 a-e so as to provide a simple system ofaligning the mating coils resulting in high interface efficiency. Thesystem of bumps and indentations might be positioned with one bumplocated at each end of each coil, or a pair of bumps on either side, orany other suitable arrangement. The source array is preferred for thebumps, as indentations would tend to accumulate sawdust or the like fromthe workplace which could impede inductive coupling efficiency. Theideal system of bumps and indentations is envisioned as having the crosssection of the upper half of a sine wave, so that a receiver array willsit casually on a source array and will tend to rotate and translateunder the influence of gravity and/or magnetic or other attraction intomaximum alignment. By proper sizing and spacing of the bumps into ashape similar to the sinusoidal undulating wave form of array, a gooddegree of interoperability may be achieved.

For power tools and other uses requiring larger amounts of power, agrooved form of source and receiver array may be employed, wherein thesurface is described by a sinusoid undulation (possibly flattened ontops to allow interface with flat surfaced interfaces) with the coilsdisposed in the convex portions of the sinusoid. This arrangementassures that when sinusoidal powered source and appliance arrays arelocated proximate to each other, inductive interaction of source andappliance coil arrays is maximized. Sinusoids could be transverse toeach other, such as in a power tool power cord/strip so as to facilitaterolling up of cord/strip, or longitudinal (if such axes areidentifiable).

Another form of inductive interface system formed in accordance with thepresent invention may consist of a source array disposed on the end ofan extension cord which would engage with a secondary array disposed ona power tool or other device. This could provide power for 100% dutycycle even with the heaviest of usage, and yet be readily disconnectedat any time, merely by manually applying tension, or via one of thedisengagement devices discussed hereabove. Another form of the inventionincludes a small table/toolrest with source arrays in the surface, withthe table having extendable legs that allow the table to be positionedwhere needed.

A major feature of the “Universal Inductive Interface Power ConnectionSystem” comprising the present invention resides in the fact that whileconfigurations and densities of source and appliance arrays may beoptimized for different applications, different sources and receiversare at all times interoperable. For example, a flat surfaced array maybe employed with a sinusoid surfaced array and vice versa. As a generalrule, the maximum current available for power transfer will be afunction of interface area, inductor density and the coupling efficiencyfactor. With a standardized source coil density, the secondary arraymaximum voltage will be a function of appliance coil density, as in anytransformer.

Referring to FIG. 14, all forms 602 a-d of the source array which mightbe desirable on a job-site or in a home or office, would have both aplug 604 for receiving power from wall socket or other source 606 and asocket 608 or more so that other forms of course array may be connectedtogether to provide a broad spectrum of recharging possibilities. Forexample, a long power cord array could stretch the entire expanse of ajob-site, providing opportunities along its entire length for a modestrate of recharging, and forms of source arrays such as a pad comprisingthe upper surface of a shelf of a work table could be connected to andderive power from the conductors of this power cord. This would providefaster recharging than otherwise available. It would also provideefficient recharging at locations on the job-site of heaviest tool use.Source pads or other containers for the source inductor coils employedin the charging system of the present invention may advantageously beset upon tables, workbenches, saw horses, shelves or the like to relievethe worker of the current necessity of bending over each time it isdesired to put down or pick up a tool from the ground, which iscustomary practice at most construction sites. A single source inductorarray located on an extension cord may be connected at another location,with a sinusoidal undulating source array at another location and a bumparray at another, to provide additional recharging opportunities. Thedifferent source arrays could also transfer power to each other throughtheir inductive interfaces. Thus, there would be no further need for aconventional plug and socket connection to recharge the device.

It is preferable to provide for positive engagement between the receiverand the source. This may prove useful when the source is positionedother than in a horizontal position and when the interface is subjectedto vibration or jostling, since it produces a tighter magneto-inductivecoupling (between source and appliance) by ensuring the best proximityand/or alignment of coils. This, in turn, helps overcome possiblemagnetic repulsion between the coupled sets of source and applianceinductors. This desirable result may be achieved by provision of amagnet, e.g., a permanent magnet, in the center or edge of eachrepeating coil unit of the appliance or source coils to mate withanother magnet or magneto attractive mass positioned in the center oredge of each repeating coil unit of source or appliance coil,respectively.

The iron or other core material employed in each inductor coil has asufficient degree of permanent magnetism to function as engagementdevices, since these cores are ideally located for this purpose. Ineffect, the magnetic attraction is sufficient to open the coil switchand thus operate the charging system. However, it could be that thedegree of permanent magnetism needed to align the coils is incompatiblewith the electro-magnetizability (permeability) required for the core tofunction efficiently in an inductor, in which case the alignment magnetmay be set orthogonal to the inductor primary axis of the “x-y” plane,preferably mutually centered, as shown in FIG. 8.

If each coil has a degree of mobility at each of its ends approximatelyequal to half the spacing between coils, intercoil spacing will allowthe pairs of coils to assume alignment. Such mobility of the coils canbe achieved by using braided wires in the coil connections and a housinglarger than the diameter of the coils. This allows the coils to slide inthe x-y plane, wherein one surface of the housing is the interfacesurface of the source array. Alternatively, Velcro™ mating tongues andgrooves in the source and receiver or mating physical structures may beemployed as engagement members. In each of these embodiments, the factthat the housing is larger than the size of the coils makes it possiblefor the pairs of coils to achieve proper alignment. Alternatively, thehousings for the source and appliance arrays could be magneticallyattractive to each other.

Once the source and appliance coils are brought in proximity with eachother, a disengagement device may be required to break theelectromagnetic bond. Disengagement may be effected by physically movingthe appliance away from the source, reducing the magnetic coupling.Alternatively, if a magnet functions as an engagement device, it couldbe mounted in an opening in the appliance such that the magnet could bemoved within the appliance away from the source, in the z direction awayfrom the interface, thereby reducing the magnetic force of engagement.This movement could be achieved mechanically by the squeezing of atrigger in the appliance, or electrically through a trigger switch.Alternatively, a contact detector responding to a user's touch could beemployed. The detector actuates a solenoid connected to the engager,pulling away from the interface. Disengagement is achieved by sending aback voltage through any activated secondary coils, so as to generate arepulsive magnetic force against the primary coils. Alternatively, aforward voltage could be sent through the activated receiver coils ifthe inductive coupling generates a net repulsive force which inoperative engagement must be countered by the attachment system, therebyincreasing the repulsive force in the inductive coupling and overcomingthe attachment force.

So as not to waste power in systems where primary coil to secondary coilalignment is not assured, either the theoretical maximum voltage outputof the appliance array should be higher than the desired output by afactor inverse to the cosine of the greatest operational misalignment ofa coil-set and any excess voltages diverted and added with other excessvoltages from other coil sets and input to the appliance, or thesecondary coils can be multitapped, with the tap producing optimalvoltage automatically selected by a trimmer circuit. Alternatively, themaximum theoretical output voltage can be set equal to a desired inputvoltage, and voltage multiplier circuits used to increase any lowvoltages resulting from any misalignment. Exact voltages are achieved byusing conventional means, i.e., variable resistors, to split theoriginal voltage, only multiplying a portion of it, which is added backor by any conventional arithmetic circuit.

It may be desirable to include a battery/fuel cell overcharge preventioncircuit, which would operate to disable the system either byelectrically isolating the engaged secondary coils or, preferably, byturning off the coil switches of any source coil actuated due tosecondary coil proximity. Alternatively, the secondary coils could bephysically relocated within the body of the appliance, to reducemagneto-inductive interaction.

A rechargeable fuel cell system may be employed with the inductiveinterface as the recharging device, wherein the secondary array in thepowered device will, after receiving power from a source array, causethe fuel within the fuel cell to be regenerated from the oxidationproducts of the fuel cell's operating reactions. For example, in ahydrogen fueled system, the hydrogen fuel for the fuel cell would bestored in the form of a metal hydride, a saturated graphite orfullerance (possibly doped with electrophiles such as lithium and/orelectrophos), or compressed gas, which in the absence of power from aninductive coupling of the secondary array, would react with atmosphericoxygen to produce electricity and water. The water would be stored andthe electricity used to power the device. When later connected to asource power array and receiving power through inductive coupling, thestored water would be reduced by hydrolysis using electric power fromthe inductive coupling into hydrogen which would be stored in the abovecited storage device, and oxygen which would be released to theatmosphere. If the system lost its hydrogen, it could be replaced aswater, and hydrolysis would occur as stated above through the inductivepower transfer, to put the fuel cell system back into a chargedcondition.

In a preferred embodiment of the present invention, a power tool havingone or more inductive secondary coils formed in accordance with thepresent invention may be laid to rest on either side on a source padhaving an array of built in primary coils. Secondary coils arepositioned in the bottom and/or along the sides of the tool, or may belocated in the bottom of a battery pack which itself may be detached andreplaced. Whether the secondary coils are mounted in the power tool orin an attachment to the tool, by positioning the power tool with itsinterface (inductor secondary array) on a source pad or similarreceptacle including the source inductor array, it becomes possible tocharge the power tool between operations, merely by placing the tool onthe source pad, thus maintaining a sufficient charge in the power toolat all times. The extra batteries or fuel cells could be recharged onthe same source array.

For extremely severe use, the source array could be set on an incline sothat exhausted batteries would be set at the top of a sequence ofbatteries on the incline, and the battery which has charged for thelongest period of time could be withdrawn from the bottom of theincline.

A job-site source array might take the form of a coilable flat powercord ribbon about ½-inch thick by 2-6 inches wide by any length from2-100 feet. Workers conveniently lay their tools on the ribbon when notin use. The edges could be tapered to prevent tripping. One end ribbonmay have a cord adaptable to being plugged into a conventional electricoutlet. It could also have sockets into which may be plugged otherappliances and source arrays. The flat power cord ribbon could have acentral stripe of ferrous material with a separate strip of source coilscomplete with coil switches and supply conductors on either side. Theribbon would be designed to mate with a receiver array consisting ofpolygonal cells of diameter equal to the spacing of the two strips ofsource coils, composed of secondary coils with supporting circuitry andwith a magnetic button at the center of each polygonal secondary array,thereby assuring good coil alignment.

In all instances in which an inductor has been described as being in thex-y plane, i.e., its longitudinal axis parallel to the plane of theinterface, an inductor being in the z direction, i.e., its axis normalto the plane of the interface, may also be provided, and an inductivearray may contain both parallel and normal inductors.

A signal can be transmitted through the same inductive array whichtransmits power from a source to an appliance by injecting the signalinto the interface at an appropriate frequency through an appropriatefilter and removing it on the other side of the interface throughanother appropriate filter. In this way, computers and all types ofportable and non-portable devices can communicate when they are engagedthrough an inductive interface.

While the preferred forms and embodiments of the invention have beenillustrated and described, it will be apparent to those of ordinaryskill in the art that various changes and modifications may be madewithout deviating from the inventive concepts set forth above.

A wire which upon sensing the presence of an inductor which seeks toestablish an inductive mating (interface) with it, will coil itself soas to form an inductor.

This wire may be initially disposed as a loose coil or array of coilswithin a broad flat cavity defined on the mating surface side by a thinwall, as in FIG. 15 a. These coils would increase their curvature (i.e.tighten their radius) when in the proximity of the mating inductor, soas to increase the number of coils there (thus increasing the amount ofinductor there) at the expense of the number of coils elsewhere. Ineffect, the coils, which were built into the wire, would migrate to theinterface location and achieve the correct alignment, as in FIG. 15 b,until maximal concentration of the coils at the inductor mating locationis achieved, as in FIG. 15 c.

In the embodiment as described above, the wire-coils are dispersedflatly in the housing cavity for a z-axis coupling (i.e. solenoid axisorthogonal to the mating surface) FIG. 15 a-c.

In an alternative and equally valid embodiment, these coils would havetheir solenoid axis in the x-y plane, i.e. parallel to the matingsurface. In this case, there would be relatively many coils of a smallerdiameter, as is known from conventional inductor design. As in theprevious example, the coils would be somewhat loosely dispersed in thecavity (FIG. 15 d), until a mating inductor made it's presence felt, atwhich point the coils would begin to coalesce adjacent to it as in FIG.15 e and finally constitute a fully formed inductor as in FIG. 15 f.

It should be understood that it may be a physical property of the wireof these coils which causes them to tighten their radius and coalesceinto an inductor, or it may be a property of the insulation or of anelement parallel to the wire, such as a piece of nitinol or othershape-memory or shape-changing material, or it may be a specificallyresponsive servo-mechanism with micro actuators dispersed along thelength of the wire.

Specifically examining the example of a nitinol or other shape-memorywire embedded with (301) or identical with the inductor wire (302), inthe same insulation sheath (303), as in FIG. 16. The hot condition ofthe nitinol (etc.) would be the tighter radius of curvature as in FIG.18, versus the cold condition or shape which would be the looser radiusof curvature as in FIG. 17. In one embodiment said hot condition wouldbe invoked by the waste heat from the (initially small) induction in theregion where the mating inductor has been placed, which said heat andsaid inductive coupling will progressively reinforce each other untilall or most of the formerly loosely arrayed coils are tightly clusteredinto an inductor, adjacent to and coupled with the mated inductor whichcaused it to coalesce, into an inductor, as in 15 a-c and 15 d-f.

In an x-y axis coil-inductor, since there are many coils diameter it maybe desirable to have the nitinol or other shape-changing element asdescribed above, not run parallel to the conductor, but form a mandrelabout which the wire coils. This mandrel could be a coil of the samediameter(s) as the conductor coil, but with a fraction of the helicalpitch (i.e. # of coils length), and affixed to the insulation at eachpoint of crossing, or even to the wire itself, if the shape-changingcoil is a sufficiently weak conductor as to not divert current from theconductor-inductor wire (which could heat and deform the entire lengthof the shape-changing element). (Alternatively, it may be that bybalancing the conductivity of the nitinol etc, with the main wire, asmall portion of the total current would go through the nitinol etc. andheat it causing it to curl as desired, if there were coil switchesdispersed along the whole coil length, so that only the region inproximity to the mating inductor were energized.) The reason for havingless turns of the shape changing element is that then for a given massit could be thicker and thus exert more force. Of course, the shapechanging component could be a solid or tubular core for the inductorcoils, which shortens in proximity to the mating inductor, due to heat,or the presence of electric or magnetic fields, thus causing the coil toconcentrate in this region. It could be plastic. It could be theinsulation itself

The mating inductor could send out a signal which turns on the coilcoalescence system, and this signal could also activate the coilswitch(s) which allows electricity to pass through the coil. It shouldbe understood that these above forms of inductor could operate free of ahousing.

In another preferred embodiment, when it is desired for discreteinductors to be mobile within their apparatus so as to achieve alignmentwith a mated inductor, as described in the parent application Ser. No.09/702,234 (which is incorporated by reference, and beginning pg 10 In.17 through pg. 12), the mobility and alignment of said inductors may beachieved by equipping each mobile inductor with a sensor means to detectproximity and direction of/the mating inductor, connected to a motioncausing means which moves the inductor in the direction indicated by thesensor. This motion causing means could be small motorized wheelsassociated with the inductor, which wheels bear upon the inside surfaceof the broad flat cavity parallel to the mating surface in the apparatusin which the inductor is to move about. These wheels (or wheel) wouldmove the inductor into mating alignment.

For x-y inductors, both translational and rotational alignment would berequired to be made by this alignment mechanism, the 3 degrees offreedom (x,y, and rotational) requiring at least 3 mechanisms. For az-axis inductor, since it has rotational symmetry in the x-y plane, onlytwo degrees of freedom exist and only two directions of motion arerequired. This could be done by an x-axis mechanism (such as a motorizedwheel or jack screw or other mechanism) and a y-axis motorized wheel orjack screw or other mechanism, or it could be achieved by a single wheelwhich pivots, with one motor or means to pivot the wheel for movement inany direction such as is determined by the sensor to be toward themating location, and another motor or means to roll the wheel towardsthat point. In a possible preferred embodiment, that single wheel couldbe centrally located in the core region of the inductor it could be aspherical wheel. The overall appearance would be similar to a computermouse. FIG. 20 a shows a top view of such a mobile inductor, and FIG. 20b shows the side view of same. 601 is the inductor coils, 602 is thewheel, 603 is the rolling motor, 604 is the pivoting motor, 605 is thesensor, 606 is the housing cavity, and 607 is the pivot axis.

FIG. 19 a shows a side view of an x-y axis mobile inductor sensing amating inductor and moving into (translational) alignment. FIG. 19 bshow alignment achieved. In these FIGS. 501 is the sensor, 502 is themating inductor, 503 is the device powered by the inductor's interface,504 is the inductor housing with a broad flat cavity for the mobileinductor, 505 is the mobile inductor, 506 is the motor connected to thewheel 507 which moves the inductor, And 508 is the connection by whichthe sensor controls the motor(s). FIG. 19 c is a top view of the samex-y inductor showing the wheels pivoted by another mechanism so that theinductor may achieve rotational alignment with its mating inductor.

In another important embodiment of the invention; the inductor array iscomposed of a 2-dimensional (x-y) tessellated grid of inductor elements(as described in the parent application Ser. No. 09/1702,234), in whicheach element of the grid is a conductor or small inductor element whichwhen a plurality of these are electrically energized in the correctpattern such as in direct response to the presence of a mating inductor,will constitute an inductor of sufficient power and such orientation asto inductively transfer power to the mated inductor. Each grid elementwould in response to the field information from the mating inductor,orient its axis of conduction or induction in the correct direction sothat the required inductor was created. Within each grid element thiscould occur by selective activation only of those conductive orinductive elements of a multiplicity of such elements 701 running indifferent directions as in FIG. 21 a, which are running in the requireddirection 703, due to the influence of mating inductor 702 (which isshown elevated above it for ease of illustration) as in FIG. 21 b, or itcould be achieved by rotation of the grid element which only containsone direction of conductor or inductor, into the correct orientation, asin FIG. 22 a-b with FIG. 22 a showing the disorganized state wherein 801are the randomized grid elements and FIG. 22 b showing the inductororganized under the influence of the mating inductor 802 (again showndisplaced for ease of illustration) and 803 being the directionalorganized grid elements.

Each grid element could have its own power connections, so that thesystem would be independent of establishing perfect connection betweenall of the grid elements required to be connected to constitute aworking inductor.

1. A power transfer system, including power connection means, saidsystem with at least one inductor in which said at least one inductor ismobile such as to achieve alignment with another inductor for inductivepower transfer to occur.
 2. The power transfer system as recited inclaim 1, wherein the said at least one mobile inductors are mobilewithin a housing.
 3. The power transfer system as recited in claim 2,wherein said external housing does not change shape when the at leastone mobile inductor(s) moves.
 4. The power transfer as recited in claim3, wherein said housing has a thin flat external wall, and wherein saidat least one mobile inductor moves along the inner surface of saidexternal wall, in order to seek alignment with an inductor placed inproximity to the external surface of said external wall.
 5. The powertransfer system as recited in claim 4, wherein there is a broad flatcavity parallel to said external wall, the upper bound of which is theinner side of said external wall, and the lower bound of said broad flatcavity is a second parallel external wall, configured to provide spacefor movement of said at least one mobile inductor.
 6. The power transfersystem as in claim 5 wherein said second parallel external wall may restupon any existing surface.
 7. A power transfer system, including powerconnection means, said system with at least one inductor in which saidat least one inductor is mobile such as to achieve alignment withanother inductor for inductive power transfer to occur wherein there isat least one sensor which can detect proximity and relative direction ofa mating inductor, said sensor connected to and controlling at least onemotion causing means so as to move at least one of said mobileinductor(s) into effective alignment with said mating inductor so thatinductive power transfer may occur.
 8. The power transfer system ofclaim 7, wherein said motion sensors are placed within or adjacent tosaid at least one mobile inductor.
 9. The power transfer system of claim1, wherein said power connection means to each said at least one mobileinductor(s) is a wire connected to the power supply or load.
 10. Thepower transfer of claim 1, wherein said power connection means to eachmobile inductor is at least one brush or sliding electrical contact 11.The power transfer system as recited in claim 10, wherein said brushesor sliding electrical contacts slide-ably make electrical contact withthe said inner surfaces of the said housing in which surfaces areconductive and connected to said power supply or load.
 12. The powertransfer system as recited in claim 11, wherein both inner surfaces ofsaid housing are conductive, and are assigned polarity so as toestablish a circuit with those of said mobile inductors which areenergized.
 13. The power transfer system as recited in claim 1, whereinthere is only one electrical connection to each mobile inductor.
 14. Thepower transfer system as recited in claim 7, wherein said motion causingmeans is non-mechanical.
 15. The power transfer system as recited inclaim 11, wherein all of said mobile inductors which are energized areeffectively connected in parallel.
 16. The power transfer system asrecited in claim 1, wherein there is at least one capacitor connected toeach of said mobile inductors.
 17. A power transfer system whichincludes a power connection means and at least one mobile inductor,which is also a flexible inductor wherein said flexible inductor whichis sufficiently flexible so as to be able to allow at least a portion ofits length to bend and migrate so as to achieve alignment with anotherinductor for inductive power transfer.
 18. The power transfer system asrecited in claim 17, further including a housing, wherein said flexibleinductor is free to move within said housing.
 19. A power transfersystem as recited in claim 17, said flexible inductor beingself-reconfigurable due to the properties of said at least one flexibleinductor, said properties so as to optimize inductance at a given regionwith a mating inductor.
 20. The power transfer system as recited inclaim 17, wherein said flexible inductor is capable of actively changingits shape.
 21. The power transfer system as recited in claim 1, whereineach mobile inductor includes a switch, said switch operable in theeffective presence of a mated secondary inductor seeking power transfer.